Spherical glassy carbon/AlN microwave attenuating composite ceramics with high thermal conductivity and strong attenuation. Issue 13 (September 2020)

• Record Type: Journal Article
• Authors: Fang, Xia; Pan, Limei; Yin, Shuang; Chen, Hongxing; Qiu, Tai; Yang, Jian
• Is Part Of: Ceramics international. Volume 46:Issue 13(2020)
• Page Start: 21505
• Page End: 21516
• Publication Date: 2020-09
• Subjects: Glassy carbon/AlN composite -- Thermal property -- Dielectric property -- Microwave absorbing property; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2020.05.252
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: High density spherical glassy carbon/aluminum nitride (GC/AlN) microwave-attenuating composite ceramics were fabricated using hot-press sintering. The effects of GC content on sintering, mechanical, thermal, electrical, dielectric, and attenuating properties were systematically investigated. Addition of GC inhibited densification and AlN grain-growth. Strength decreased monotonically with GC content up to 12 wt%, whereas the toughness increased and then decreased. The spherical morphology of GC gives the composite higher thermal conductivity and conductivity percolation-threshold compared with AlN-based composites containing non-spherical second phases. Enhanced conduction loss, polarization loss and mini-capacitor effect result in a consistently increasing dielectric constant and loss, and an increasing and then decreasing reflection loss (RL). The 6 wt% sample exhibited an RLmin of −22.21 dB and a high thermal conductivity of 70.58 W·m −1 K −1 . This work provides a novel strategy for preparing microwave-attenuating composite with combined high thermal conductivity and strong attenuation using spherical GC attenuating agent.